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    <title>Document</title>
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    <div class="col-sm-3 col-md-2 sidebar">
        <ul class="nav nav-sidebar">
          <li class="active"><a href="#">所有学生 <span class="sr-only">(current)</span></a></li>
        
          <li><a href="#">web班</a></li>
          <li><a href="#">运维班</a></li>
          <li><a href="#">UI1班</a></li>
          <li><a href="#">UI2班</a></li>
        </ul>
        <!-- <ul class="nav nav-sidebar">
          <li><a href="">Nav item</a></li>
          <li><a href="">Nav item again</a></li>
          <li><a href="">One more nav</a></li>
          <li><a href="">Another nav item</a></li>
          <li><a href="">More navigation</a></li>
        </ul>
        <ul class="nav nav-sidebar">
          <li><a href="">Nav item again</a></li>
          <li><a href="">One more nav</a></li>
          <li><a href="">Another nav item</a></li>
        </ul> -->
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